Housing with intersecting passages for high pressure fluid applications

A housing (30) for use in high pressure fluid applications comprising a first drilling (32a, 32b), defining a first axis, and having a region of enlarged diameter (32b) bounded by an upper boundary (36) in a first plane and a lower boundary (38) in a second plane; and a second drilling (42), defining a second axis, and intersecting with the first drilling (32a, 32b) via an intersection region (44). The intersection region (44) includes a first substantially flat surface (54) which defines a ceiling of the intersection region (44) and which intersects the upper boundary (36) of the region of enlarged diameter (32b), and a second substantially flat surface (56) which is opposed to the first substantially flat surface (56) and which defines a floor of the intersection region (44) and intersects the lower boundary (38) of the region of enlarged diameter (32b). As the flat surfaces are in alignment with a region of maximum hoop stress (i.e. at the upper and lower boundaries of the enlarged diameter region of the first drilling) they do not act as a significant stress raiser at the intersection (44). In another aspect of the invention the first drilling need not have a region of enlarged diameter, with the intersection region having tangential surfaces to the circumference of the first drilling so that the intersection region does not intersect with a region of hoop stress.